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G. E. BEGGS.

AEROPLANE BOMB SIGHT.

APPLICATION mu) MAR.29.19!8.

Patented July 5, 1921.

4 SHEETSSHEET I.

awvawfoz 0 .4 al: fil b. 13 414M m G. E. BEGGS.

AEROPLANE BOMB SIGHT.

APPLICATION FILED MAR.29, 191B.

1,883;969. Patented July 5,1921.

4 SHEETSSHEET 2.

nuamfoz 29.2074 611:

G. E. BEGGS.

AEROPLANE BOMB SIGHT.

APPLICATION FILED MAR. 29, 1918.

Patented July 5, 1921.

4 SHEETS-SHEET 3.

A as. 00 m M wue'wl'oz 1 4 1 J31 G. E. BEGGS...

AEROPLANE BOMB SIGHT.

APPLICATION FILED MAR. 29, 1918.

1,383,969. ted July 5, 1921.

| 4 SHEE]'SSHEET 4. F z 'qlfl Time to traverse Time to traverse distancedistance D TD secs. ED TA secs.

Dft.

Path of Aeropla ne E D A C Known distance =ground-speed of aeroplane inmiles per hour.

g =acce|eration of gravity 32.|84 ft/sec at Paris.

EQUATIONS FOR ANGLE OF AiM a For: SET i 0F SiIALES ExpressedAlgebraically Expressed logarithmically I H 2 |og.cotan.6= FIGZ cocan 5=iog.H |.2O66| E9 TA co|0g.T

I 2 lo .cotan.6= FIG.6 v cotan |og.D- |0 .TD

T colog.TA -I.ZO66| 2 2 |og.cotan. d FIG-7 cotan co|og.H O.87395 ZlogJUamvewfo z um e 6% 24%. $513k? axiom L015 plane,

the time which it will take PATE orrics.

GEORGE ERLE BEGGS, or PRINCETON, NEW-JERSEY.

anaortann BOMB-SIGHT.

Specification of Letters Patent.

Patented July 5, 1921.

Application filed March 29, 1918. Serial No. 225,467.

To all'whomitmag concern:

Be it known that I, GEORGE E. Bases, a citzen of the United Statesresidin at 73 Jefferson road, county of Mercer, rinceton, New Jersey,have invented certain new and useful Improvements in AeroplaneBomb-Sights, of which the following is a specification. f

y invention relates to mechanism adapted for use in adjusting sightingpoints carried upon an aeroplane for the purpose of ascertaining byreference to said sights the correct time, during the flight of anaeroat which to release a bomb or other missile or package in order tohave it strike a selected objective.

hen a missile or other package is dropped from a moving aeroplane, thecourse which it will follow in its fall will be substantially determinedby the momentum which it has acquired from the moving aeroplane, and bythe attraction of gravitation. If, for instance, the aeroplane is flyingin a horizontal plane, the missile, when released, will tend to continueforward in the same direction, but willbe pulled down with increasingrapidity by the attraction of the earth. This being so, the point A(Figure 9) .at which the. missile begins its fall, and the point B nuseofa right angled triangle the perpendicular of which is a vertical lineB, C, and the base of which is the line'A, C.

Therefore, if the altitude of A, andthere fore the length of the line B,C, is known, the missile to fall from A to the ground may be readilycomputed; and, if the initial horizontal speed of the missile is alsoknown, the extent of its forward movement, during the time of its fall,in other words the length of the line C- may also be determined. And, ifthe aeroplane carrying the missile is moving in .-a horizontal formspeed, the inclination of the line A, B may be determined in advance,and mechanical sights adjusted to that angle of inclination, so that ifthe missile is released when the "objective point is seen from theaeroplane to be at B of the line A, B, its curve of flight will be suchas to cause it to strike at B, proper allowances being of course madefor air resistanceand other minor modifying conditions.

Because of the rapidity of flight of aeroidly, and so at which itreaches the ground,- I will be at the respective ends of the hypoteablescrew 4 threaded into the plane at a substantially uni planes, theconditions under which the aviators operate, and the difliculties whichare often encountered in seeing an objective, it is of great importanceto make the necessary observations, calculations and adjustments forsighting, not only accurately but rapfar as possible automatically. Andit is to means for securing these ends that my present invention isparticularly directed, these means embracing means for ascertainingaltitude and speed, and by relatively adjustable computing members mechanioally determining the angle of inclination of A B from thehorizontal and automatically setting adjustable sights at that angle, asT will now proceed to explain, referring, in so doing, to the drawings,which illustrate a preferred form of my invention, and in which Fig. 1is a side elevation, partly broken away for clearness; Fig. 2 is a topviewyFig. 3 is a cross sectional view on theline 3-3 of Fig. 1 lookingto the left; Fig. 4 is a detail on the line 44- of Fig. 1, looking up;Fig. 5 is a detail of the rotatable sight; Figs. 6, 7 and 8 illustratemodifications in the computing scales for use under varying conditions,Fig. 9 is a diagram illustrating sighting angles and Fig- 10 shows,diagrammatically, the method of computing the angle of aim and theequations by which it 1s derived under different conditions.

A base 1 is attached to the frame work of the aeroplane in any suitablemanner; and above it is mounted .a case 2, which is secured to the baseby pivots as 3, 3, at one end, and at the opposite end by an adjustbaseat 5. This arrangement permits of the leveling of the case as a wholesTo the case are attached spirit levels 6, 7 adjusting screws 8,.8-threaded into brackets on the case whereby the levels may be adjusted intheir relations to the case.

The object of these adjustable features is to permit the adjusting'ofthe apparatus to the normal position of an aeroplane when flying on ahorizontal plane. rotatable sight 9 and'fixed sights 10, 11 and 12 areeach detachably secured to the case being attached as by' means of ascrew threaded capjfas 13, threaded upon a stud as 14, fastened into orthrough These sights 9, 10, 11 and 12 are preferably so set that theinclination of the line 9ll is 45 vdegrees below the horizontal, asDBwhich have suitable.

the side of the case.

Fig. 9; a line through 9-12 is vertical, as

EEG will be double that of DUB when the line E, B is taken over thesights 9-10. A

movable and adjustable sight 15 is carried by mechanism within the case.

This latter mechanism embodies an arm 16 which is pivoted at 17 on theinner end of the stud 14: and swings from that stud as a center. A link18 is pivoted at one end at 19, to the arm 16, and at its other end, at20, to one end 21 of an arm 22 hung upon a pivot pin 23 the ends ofwhich extend through slots in the sides of the case 2. The ends of thispivot pin 23 are carried by side flanges or lugs 24:, 2d on the sides ofa movable indicator 25, which is associated in a sliding relation'withthe top of the case 2, as by tongues 26 traveling in grooves 27 in thesides of the case. This indicator 25 is preferably provided with a glass28 with the usual cross line 29; and the side flanges 24 may bedetachably attached to the indicator as by set screws 30, 30 passingthrough the flanges and threaded into the indicator.

(This permits of the removal of the indicator by withdrawing the setscrews and,

ting of the movable sight 15 (Flg. 1), de-

loosening the side flanges 24:, if desired.

Upon the top of the case are carried several scales .as 31, 32 and 33.;the scales 31 and 33 being preferably fixed, while the scale 32 ismovable longitudinally, being shownas carried upon a base 34 dove-tailedinto the top of the case 2, so as to slide to and fro therein. I preferto place flat springs as 35, 35 between the top of the case 2 and thebottom of the base 34 to press the base snugly upward in its dove-tailso as to prevent its being too readily shifted or jarred out ofadjustment; and similar springs 36, 36 are preferably interposed betweenthe side flanges 24 of'the indicator 25 and the case 2, to hold theindicator against too easy displacementfrom the positions to which itmay be adjusted from time to time.

Any suitable meansfas a knob 37 may be attached to the base 34; forconveniently grasping it by the hand of the operator.

One end of' the pivot 38, which connects the arm 22 and the link 18,extends through a cam slot 39. formed in a suitable guide 40 attached tothe inside of the case 2, the pin 38 being provided with a head 11 whichserves to prevent it from escaping from the cam slot 39.

.It will be seen, therefore, that if the indicator 25 is slid forward orbackward on top of the case 3 it will carry, through its flanges 2d, 24and the pivot pin 23, the upper end of the bar 22 forward or backward,and will cause its lower end to raise or lower the connected end ofthelink 18 along the cam slot 39, and, through the link 18, to

swing the arm 16 to and fro on its pivot 17,

issaeee with the result that the sight 15 will be swung forward or backin relation to the sight 9 a distance which will be regulated by themovement of the indicator 25 along the top of the case 2, the sight 9revolving with the stud 14 so that its angular edge always .maintainsthe same relation to that of the sight 15. 1

lnthe drawings I have illustrated my ap paratus as provided with scalesadapted to furnish three classes of readings. Thus the scale 31 isgraduated togive barometer readings, and the scale 33 is graduated togive angle readings in degrees, while the scale 32 is graduated to givetime readings in seconds. It will be understood, of course, that Theangle of aim, which governs the setpends primarily on the height offlight and the ground-speed (air-speed 1 wind) of the aeroplane; that isthe angle of aimzfunction" of height and ground speed. But height may beexpressed trigonometrically in terms of other lengths and certain anglewhile ground-speed may be stated functions, It th is. erein terms ofdistance and time.

fore evident that the angle of aim itself may be expressed as a functionof otherunits than height and ground-speed, if these latter terms bereplaced by expressions mathematically and physically equivalent. makingsuch substitutions, several algebraic andlogarithmic equations have beenderived which express directly and explicitly the angleof aimin suchquantities as may readily be obtained by instrument observatlons madeduring flight, for example, barometer,

air-speed, ground-speed, and. time observations.

Four algebraic equations for thls angle of aim follow below. The personfamiliar with the application of the laws of" motion and with theequations for falling bodies, can readily check these equations.

H z (1) Got 5 g) A D 2 (2) s' teg) I slghts. .(See Figsl be expressedlogarith g The derivation of the abo and In the above equations, thenotation has the meaning defined be ow:

8=angle of aim in degrees.

:angle between the horizontal and the line' 9-15 of the movable sight.(See Fig. 1.

45=angle between the horizontal and the line of the fixed sights 9-11.(See Fig. 1.) 26-3{l':angle between the horizontal and the line of thefixed sights 9,-10. See

- Fig 1.) H :altitude in feet that the aeroplane is above theelevationof target.

T =time in seconds between the time that target appears on the line 9-10of fixed sights and later on 1 and 10.)

g=acceleration of gravity in feet per second squared=32.l84 at Paris.

zground-speed of aeroplane in miles per hourzair-speed i wind.

TD=time in seconds for aeroplane to traverse a known'distance D feetmeasured with reference to groun he four equations (1), (2), (3), (4:)may I mically by writing the logarithmic expressions for the left handand right'ha'nd members of said equations. This is done in equations(5), (6), (7), (8) below. The actual logarithms of all constant factorsare introduced and several 00- 'logs. are employed in order to bring theexpressions into the desired form for most I convenient solution onspecial slide rules.

(5) 2 log cot 8: (log H-1.20661) +52 0010 T 210g cot 8: log D? 'logT1 1) colog 1.2066

1+colog H) g 52 1.0g TD) colog H1.20661) 7) 2 log cot 6; 1.87395 asfollows (see Fig. "10) ED=DC=GT =H 1 H =altitude in feet =groundrspeedin feet per sec.

V ground speed in miles per hour .3600 15 v a *TT 5 G 3 DC:-DA+AC aDA=H-H cot a 4 AC=Gt ,5

the line 9-11 of fixed ve equations is spectively.)

'cam and leve where t equals the time of fall for bomb in seconds. Q =9whence 2 t= f 7 I v g Fromm,

,H=HH cot 6-{ Gt (8) l 2% 5 I cot6 T (9) Squaring v H cote- (10 which isformula for scales in Fig. 2.

Again,

Whence which is formula for scales in Fig. 6.

Again from (11) Whence HTD'eg') (14) which is formula for scales in Fig.8.

From (10) and (11) a Li" cot Le 4 -(%g)H (15) From (1a) and (15 We) cotL H E 484 which is formula forscales in Fig. 7.

The logarithmic quantities given in the brackets of equations (5), (6),(7), (8) have been laid out on the sparallel scales of the ee Figs. 2,6, 7, 8, re-

cot 6 special slide rules.

and 3.)

-posi- The set of scales shown in Fig. 2 is adapted to solve theequation given as (5) above. The algebraic and logarithmic statements 7of this equation and of others to follow are i the characteristic of thelogarithm of the scale 33 at the line -60 shall be zero, and that oi thescale 31 shall be 20661; andthe characteristic otthe logarithm of thescale 33 at 61-61 shall also be zero, and that of the scale 31 at theline 61-61 shall be .20661.

ln a.

similar manner the scale 32 is laid out, when in ite initial position asin Fig. 2, between the lines 60-60 and 61-61, taken as bases, so thatthe characteristic of the logarithm of the graduation at each of saidlines shall also be zero. Hence it will be seen that it the scale 32 isadvanced relatively to the scale 31 so that its index arrow at zeroshall be opposite any selected altitude reading on the scale 31, thegraduations on the scale 32 may be read forward or add ed to theselected readin on the scale 31 so as to add the logarithmical readingon the former scale to that of the latter, and so that any advancedpoint on scale '32 will in its relation to the angle scale 33 indicatethe solution of the equation above given.

My improved bomb sight may be used as follows:-

Assuming that the apparatus has been properly leveled by means of. theadjusting mechanism, and that the aviator desires to release a bomb ormissile or package, he first reads his altitude from the barometer, notshown, with which his machine is equipped. M, for instance, he findsthat his altitude relative to his objective is sixty-three hundred feet;he moves his time slide 32 until the arrow 45 at 100 stands opposite thereading sixty-three hundred on the barometer scale 31, which, results inshifting the grad nations on the time scale in their relation to thegraduations on the angle scale.

Withthe scales in this relation the avia= tor continues his fli ht untilhe has his objective in line with the sights 9 and 10, when he starts atiming mechanism, as, for instance, a stop watch 46, and continues hisflight, as nearly as possible on the same level, until he has hisobjective in line with the sights 9 and 11, when he notes the elapsedtime on his timing apparatus as by stopping the watch and reading it;for intill stance, the elapsed time might be thirty-two and four-fifthsseconds which represents half the time required to cover the base lineDC. He then moves the indicator until its registering line 29 standsover the gradu ation thirty-two and four-fifths seconds on the timescale, this results in swinging the incense arm 16 carrying the lowersight 15 into the angular position corresponding with the barometer andelapsed time readings, to wit, fifty-eight and nine-tenths degrees fromthe horizontal. He then continues his flight, always as nearly aspossible at the same al titude, until he brings his objective in linewith the sights 9 and 15, when he releases his missile, the result beingthat the initial speed of the missile derived irom the aeroplane willcarry it sufiiciently iar forward store it reaches the ground so that itshall fall at the point selected as the objective, if the calculationsand release of the missile have been accurately carried out.

I desire it to be understood that suitable allowance will have been madepreviously for the air resistance by adjustmentof the lower sight 15forward or back by means of the set screw 47 against which the sight ispressed by a spring pressed plunger 4:8, as

is common in transit instruments.

l have explained the operation of my apparatus when provided withaltitude, time and angle scales. But l wish it to be distinctlyunderstood that these scales can be varied and other scales substitutedfor them.

Thus, when it is convenient to determine ground speed by timin overlmown territory and when the con itions are such that timing on thetarget can be done with reasonable safety the barometer scale 31 wouldbe omitted and the scales shown in Fig. 6

would be used, the scale 50 representing a scaling from the map in feet;the scale 51' being a modification of the timing scale 32; and the scale33 remaining the same.

In this case the equation to be solved is that given as (6) above.

In this case the time is taken with the timing mechanism over sights 9and 12 to the ground, and the time noted by moving the scale 51 untilthe time numeral on its left hand margin corresponding with the elapsedtime is opposite the number of feet traveled on the distance scale overany known distance. The target is then sighted over sigths 9 and 10 and.timed until it is taken over sights 9 and 11, and the indicator is moveduntil its cross line corresponds with the last elapsed time on the righthand side of the scale 51. This moves the sight 15 wireless from theground, and the indicator is then moved until its cross line stands overthenumeral on scale 54 corresponding with the miles per hour.

7 possible variations of the method ing and this This brings the sight15 in proper angular position for releasing the missile when the tar etis sighted over sights 9 and 15.

he equation solved in this case is that given as (7 above.

In the system of scales shown in F i 8 the barometer scale is placed onthe rig t side of the slide which is also provided with a time scale onits left hand side. And scale 56 is for feet over a known rounddistance. The equation to be solved in this case is that givenas (8)above.

The barometer is read for elevation and the barometer scale is moved,after the time figure has been taken by ground si hting, until the ropertime figure on its le hand side stan s op osite to the distance coveredon scale 56. he indicator is then moved until it stands opposite thebarometer read again results in bringing the s'i ht 15 into the properangularposltion.

ach of these sets of scales is laid off upon the principle explained asgovernin the relative graduations on the scales of F ig. 2. In all these.systemsithe essential overning elements consist of elevation an speed.d the four systems of scales simply show of combining the readings forspeed and elevation so as to brin about an automatic adjustment of themova 1e sight 15 into its proper angular relation with the horizontal. ereason for adopting several systems of scales each based on a differentequation is one of military strate If the conditions of warfare are sucht at the observations which are necessary to operate any one set ofscales, cannot be taken, another set of scales maybe selected for usefor which the necessag observations may be made more safely. aving usdescri ed my invention what I claim and desire to secure by LettersPatent of the United States is:

1. In an aeroplane bomb-sighting mechanism, means for calculating andindicating the angle of fire from preliminary observations, embodying afixed scale graduated in terms of one element of the requlredcalcuregistering the result of lation, an associated and relativelymovable slide scale 'aduated in terms of the other elements 0 suchcalculation, coiiperating means, adjustable relative to such scales, for

the calculation, adjustable sighting means, and mechanism actuated bysaid cotiperating means for adjusting the sightingl means to a line offire corresponding to t e result of such calculation.

2. In an aeroplane bomb-sighting mechanism, means for calculating andindicating the angle of fire from prellminary observations, embodying afixed scale graduated ,in

terms of one element of the required calcuciprocating means, adjustablerelative to i such scales, for registering the result of thecalculation, adjustable sighting means, and mechanism actuated by saidcooperating means for adjusting the sightin means to a line of firecorresponding to the result of such calculation.

3. In an aeroplane bomb-sighting mechanism, means for calculating andindicating the angle of fire from prellminary observations, embodyin afixed scale graduated in terms of one e ement of the requiredcalculation, an associated and relatively movable scale graduated interms of the other elements of such calculation, cooperating means,adjustable relative'to such scales, for registering the result of thecalculation, adjustable sighting'means, and mechanism actuated by saidcoiiperating means for adjusting the si hting means to indicate theresult of such ca culation.

4. In an aeroplane bomb-sighting mechanism, means for calculating andindicating the angle of fire from prellminary observations, embodying afixed scale graduated logarithmically in terms of one element of therequired calculation, an associated and relatively movable scalelogarithmically graduated in terms of the other elements of suchcalculation, cooperating means, adjustable relative to such-scales, forre istering the result of the calculation, a justable sighting means,and mechanism actuated by said coiiperating means for adjusting thesightingl means to a line of fire corresponding to t e result of suchcalculation.

In an aeroplane bomb-sighting mechanism, means for calculating andindicating the angle of fire from preliminary observations, embodying afixed scale graduated in terms of one element of the requiredcalculation, an associated and relatively movable -scale graduated interms of the other element of such calculation, coiiperating means,adjustable relative to such scales, for registering the result of thecalculation, I able sighting means and cam governed mechanism actuatedby said coiiperating means for adjusting the sightin means to a line offire corresponding to t e result of such calculation. I x

6. In an aeroplane bomb-sighting mechanism, means for calculating andindicating the angle of fire from prellminary observations embodying afixed scale graduated in terms of one element of the requiredcalculation, an associated'and relatlvely movable scale graduated interms of the other elements of such calculation, cooperating. means,adjustable relative to such scales, for re istering theresult of thecalculation, a substantially fixed sight and swinging sight,

adj ustand mechanism actuated by said cooperating means for adjustingthe sights to a line of fire corresponding to the result of suchcalculation.

7. In an aeroplane bomb-sighting mechanism, means of calculating andindicating the angle of aim from preliminary observations of thealtitude of flight and the elapsed time between tvvofixed sights, em-

bodying an altitude scale graduated logasaid cooperating means foradjusting the of the aeroplane,

sightin means to a line of fire corresponding to t. e result of thecomputation.

8., ln aeroplane bomb-sighting mechanism, means for calculating andindicating the angle of firerfrom preliminary observations of thetraversed horizontal ground distance, of thetirne to traverse thisdistance, and ot the time taken for the line oi? vision toward thetarget to change from one fixed angle with the horizontal to anotherlarger fixed angle with the horizontal, embodying a ground distancescale graduated logarithmically in terms of the ground distance,associated with a relatively movable scale graduated logarithmically interms oi the two time measurements above defined, the relativedisplacement of the latter two scales depending on the physical constantin the calculation, cooperating means adjustable relative to such scalesfor registering the result of the calculation, adjustable sightingmeans, and mechanism actuated by said cooperating means for adjustingthe sightingmeans to a line of fire corresponding to the result of suchcomputation,

9. In aeroplane bomb-sighting mechanism, means for calculating andindicating the angle of fire fromfipreliminary observations of thealtitude of ight and the ground speed rality oi movable scalesembozdying an altitude lessees scale graduated logarithmically in termsof the altitude, and anotherassociated and rela- V tively movable speedscale graduated logarithmically'in terms of the ground speed, the latterscale carrying also an indicating element Whose relative positiondepends on the physical constant in the calculation, cooperating meansadjustable relative to such scales for registering the result of thecalcu lation, adjustable sighting means, and mechanism actuated by saidcooperating means for adjusting the sighting means to a line of firecorresponding to the result oisuch computation. 10. lln aeroplanebomb-sighting mechanism, means for calculating the angle of fire frompreliminary observations of the traversed distance, the time, and thealtitude of flight, embodying a distance scale graduated logarithmicallyin terms of the distance, an associated and relatively movable scalegraduated logarithmically in terms of the time and the altitude,therelative displacements of the graduations of the latter two scalesdepending on the physical constant in the calculation, cooperating meansadjust able to such scales for registering the result of thecomputation, adjustable sighting means, and mechanism actuated by saidcooperating means for adjusting the sighting means to a line of firecorresponding to the result of such computation.

11. In an aeroplane bomb-sighting mecha nism, means for calculating andindicating the angle of lire from preliminary observations, embodying ascale graduated in terms of one element adapted to be used in each ot aplurality of optional computations, a plueach graduated in terms of adifi'erent element of such optional calculations and each scale beingadapted to cooperate separately with the first mentioned scale,cooperating means, adjustable relative to such scales for registeringthe result of such calculations,

operating means for adjusting the sighting means to a line of firecorresponding to the result of any oxisuch calculations.

stones ants eases.

adjustable sighting means, and mechanism actuated by said co-

